Method and device pertaining to cooling of dosing units of hc dosing systems for exhaust cleaning

ABSTRACT

A method for cooling a dosing unit ( 250 ) pertaining to HC dosing system for exhaust cleaning. The dosing unit ( 250 ) for fuel and a feed device ( 230 ) to supply fuel for cooling. The steps include cooling a fuel dosing unit ( 250 ) by fuel supplied to intermittently, in mutually successive respective periods of zero operating power of the feed device, or running at certain operating powers by running a fuel feed device ( 230 ) at reduced power compared with ordinary operation. A computer programme product containing programme code (P) for a computer ( 200; 210; 500 ) for implementing the method. An HC dosing system. A motor vehicle equipped with the system.

TECHNICAL FIELD

The present invention relates to a method for cooling a dosing unitpertaining to an HC (hydrocarbon) dosing system for exhaust cleaningwhich comprises the dosing unit for fuel and a feed device to supplysaid fuel for cooling. The invention relates also to a computerprogramme product containing programme code for a computer forimplementing a method according to the invention. The invention relatesalso to an HC dosing system for exhaust cleaning which comprises adosing unit for fuel and a feed device to supply said fuel for cooling,and a motor vehicle which is equipped with the HC dosing system.

BACKGROUND

In vehicles today, diesel fuel is used as fuel in DPF (dieselparticulate filter) systems which comprise a particle filter. Theparticle filter is adapted to capturing, for example, diesel particlesand soot. During active regeneration of the particle filter, diesel fuelis supplied to an exhaust pipe downstream of an engine and is led intoan oxidation catalyst, also called DOC. In the oxidation catalyst, saiddiesel fuel is burnt and causes a rise in the temperature of the exhaustsystem. Active regeneration of the particle filter situated downstreamof the oxidation catalyst can thus be effected.

One type of DPF system comprises a container for diesel fuel. The DPFsystem may also have a pump adapted to drawing said diesel fuel from thecontainer via a suction hose and to supplying it via a pressure hose toa dosing unit situated adjacent to an exhaust system of the vehicle,e.g. adjacent to an exhaust pipe of the exhaust system. The dosing unitis adapted to injecting a necessary amount of diesel fuel into theexhaust pipe upstream of the particle filter according to operatingroutines stored in a control unit of the vehicle. To make it easier toregulate the pressure when no or only small amounts are being dosed, thesystem also comprises a return hose which runs back from a pressure sideof the system to the container. This configuration makes it possible tocool the dosing unit by means of said diesel fuel which, during cooling,flows from the container via the pump and the dosing unit and back tothe container. This results in active cooling of the dosing unit. Thereturn flow from the dosing valve to the container is currentlysubstantially constant.

As the dosing unit is currently situated adjacent to the vehicle'sexhaust system which becomes warm during operation of the vehicle, e.g.depending on the engine's load, there is risk of the dosing valvebecoming overheated. Overheating of the dosing unit may entaildegradation of its functionality, potentially impairing its performance.

The dosing unit currently comprises electrical components, certain ofthem being provided with a circuit card. Said circuit card may forexample be adapted to controlling the dosing of diesel fuel to thevehicle's exhaust system. For various reasons, these electricalcomponents are sensitive to high temperatures. Too high temperatures ofthe dosing unit may result in degradation of the electrical components,potentially leading to expensive repairs at a service workshop.Moreover, diesel fuel present in the dosing unit may at least partlyconvert to solid form at too high temperatures, potentially leading toobstruction of the dosing unit. According to an example, said dieselfuel undergoes pyrolysis in the dosing unit and is thereby at leastpartly converted to coke. Thus at least part of said diesel fuel maycarbonise. It is therefore of the utmost importance that the temperatureof the dosing unit of the DPF system should not exceed a critical level.

Cooling the dosing unit of a vehicle's DPF system is currently effectedcontinuously during the vehicle's ordinary operation as a result of saiddiesel fuel circulating within the DPF system as indicated above. Tosome extent, cooling the dosing unit during operation of the vehiclecurrently works satisfactorily. There is however always a need toimprove the performance of vehicles' existing subsystems, e.g. DPFsystems, not least from a competition perspective.

During and after operation of the vehicle a large amount of thermalenergy caused by its operation is stored in primarily the exhaustsystem. This thermal energy may be led to the dosing unit from, forexample, a silencer and the particle filter and may warm the dosing unitto a temperature which exceeds a critical value.

When the vehicle is switched off and the exhaust flow in the exhaustsystem consequently ceases, the diesel fuel dosing unit is cooled for apredetermined time, e.g. about 30 minutes, by said diesel fuel in thesame way as during ordinary operation.

This arrangement entails certain disadvantages. One is the relativelylarge amount of energy used to power the pump in the DPF system afterthe vehicle has been switched off. Any vehicle battery used to power thepump of the DPF system may thus be discharged or reach a relatively lowcharge level.

Another disadvantage of the dosing unit being cooled in the same way asduring ordinary operation is that the pump of the DPF system emitsdisturbing noise which for example a driver of the vehicle may findirritating, particularly when he/she has to sleep in the cab after adriving run or is in the immediate vicinity of the vehicle.

There is thus a need to improve current methods for cooling the dosingunit in DPF systems, in order to reduce or eliminate the abovedisadvantages.

SUMMARY OF THE INVENTION

An object of the present invention is to propose a novel andadvantageous method for improving the performance of an HC dosingsystem.

Another object of the present invention is to propose a novel andadvantageous HC dosing system and a novel and advantageous computerprogramme for improving the performance of an HC dosing system.

Another object of the present invention is to propose a novel andadvantageous method for effecting cooling of a dosing unit of an HCdosing system after cessation of an exhaust flow therein.

Another object of the invention is to propose a novel and advantageousHC dosing system and a novel and advantageous computer programme foreffecting cooling of a dosing unit of an HC dosing system aftercessation of an exhaust flow in the HC dosing system.

A further object is to propose a method, an HC dosing system and acomputer programme for reducing the risk that a dosing unit in an HCdosing system might become overheated after cessation of an exhaust flowin the HC dosing system.

A further object is to propose an alternative method, an alternative HCdosing system and an alternative computer programme for reducing therisk that a dosing unit in an HC dosing system might become overheatedafter cessation of an exhaust flow in the HC dosing system.

These objects are achieved with a method for cooling a dosing unitpertaining to HC dosing systems for exhaust cleaning which comprise thedosing unit for fuel and a feed device to supply said fuel for cooling,according to claim 1.

An aspect of the invention proposes a method for cooling a dosing unitpertaining to HC dosing systems for exhaust cleaning which comprise thedosing unit for fuel and a feed device to supply said fuel for cooling,comprising the steps of cooling said fuel dosing unit by means of fuelsupplied to it, and of intermittently, in mutually successive periods ofrunning at certain operating powers and of zero operating power, runningsaid fuel feed device at reduced power compared with ordinary operation.

Intermittently running the feed device for said fuel results in afunctionality of the HC dosing system which reduces or minimises theimpact of the HC dosing system. The feed device may be runintermittently at an operating power which achieves desirable cooling ofthe dosing unit. The feed device may be run intermittently at reducedpower compared with ordinary operation.

The feed device may be run intermittently with a predetermined intervalconfiguration. This predetermined interval configuration may be definedas operation of the feed device being deactivated at certainperiodicities and being subsequently reactivated.

This sequence of temporary deactivation and reactivation may be repeateduntil the dosing unit of the HC dosing system has reached apredetermined desirable temperature, e.g. 40 degrees Celsius.

This predetermined interval configuration may comprise catering forrewarming effects of said dosing unit. As the dosing unit according tocertain versions is fitted adjacent to an exhaust system which comprisesfor example a particle filter and other components which may transferstored thermal energy to the dosing unit, even after the latter has beencooled to a desirable temperature, it is advantageous to cater for theserewarming effects when determining said interval configuration.

Operation of the feed device may be activated on the basis of a measuredtemperature of at least one portion of said HC dosing system.

Operation of the feed device may result in cooling of said dosing unitto a temperature which is below a predetermined limit value.

Said fuel may be diesel fuel or some other hydrocarbon-based fuel.

To minimise the impact upon the vehicle, a proposed function causesoperation of the pump of the feed device of the HC dosing system to bedeactivated and reactivated any desired number of times during coolingof the dosing unit after the cessation of said exhaust flow. Accordingto a version, the pump speed is lower or substantially lower than thatemployed during ordinary operation of the HC dosing system, whichordinary operation comprises operation of the HC dosing system when thevehicle is in motion, or previous ordinary operation of the HC dosingsystem during cooling of the dosing unit after the cessation of saidexhaust flow.

With advantage, a previous need for electrical energy from a battery ofthe vehicle when its engine is off during the subsequent coolingprocedure is reduced.

Maintaining intermittent operating power of the feed device withsubstantially unchanged cooling power of the dosing unit results in lessnoise than running the feed device at full power as previously. Part ofthe inventiveness of the present invention is that it has been foundthat the cooling power of the dosing unit is reduced only marginallywhen the feed device is run intermittently.

Applying reduced operating power of the feed device with substantiallyunchanged cooling power of the dosing unit results in less noise thanrunning the feed device at full power as previously.

Despite the operating power of the feed device being reduced comparedwith ordinary operation and its being run intermittently, withsubstantially unchanged cooling power of the dosing unit, it is possibleto avoid the fuel becoming carbonised by too high temperatures andthereby causing obstruction of the dosing unit, which might entailexpensive repairs of the HC dosing system.

By reducing the operating power of the feed device with substantiallyunchanged cooling power of the dosing unit, temperature-related damageto the dosing unit's electrical components may with advantage beprevented.

Despite the feed device being run intermittently, with substantiallyunchanged cooling power of the dosing unit, temperature-related damageto the dosing unit's electrical components may with advantage beprevented.

Reducing the operating power of the feed device may entail running it ata lower speed than during ordinary operation. Reducing the power of thefeed device may result in a lower pressure of the fuel towards thedosing unit than during ordinary operation.

According to an embodiment, the power of the fuel feed device is reducedin at least one stage to a level which results in substantially nochange in the cooling power of the dosing unit but uses substantiallyless energy than in the state of the art.

The method may comprise the step of intermittently running said feeddevice at least possible power, with substantially unchanged coolingpower of said dosing unit, for as long as cooling continues. Withadvantage, a cooling function is effected whereby the cooling power ofsaid dosing unit is substantially unchanged but the impact of the HCdosing system is decreased in a desirable way.

The step of running said feed device may comprise running it at a powercorresponding to 10-30% of that during ordinary operation. Withadvantage, this results in a substantially reduction in the amount ofenergy required for adequate cooling of the dosing unit of the HC dosingsystem, particularly since the feed device is also run intermittently.According to a preferred embodiment, the step of running said feeddevice may comprise running it at a power corresponding to less than 10%of that during ordinary operation. According to an embodiment, theinnovative method may result in a total energy saving of 10-50% comparedwith cooling methods according to the state of the art.

The method may further comprise the step of running said feed device onthe basis of a measured temperature of at least one portion of said HCdosing system. Any adequate temperature of said at least one portion ofsaid HC dosing system may be used such that cooling of the dosing unitcan be switched off automatically when said temperature of the at leastone portion of said HC dosing system has been reached after cessation ofthe exhaust flow.

Running said feed device may entail catering for rewarming effects. Saidpredetermined period of time and said adequate temperature of the atleast one portion of said HC dosing system may be predetermined by acomputer model stored in a control unit of the vehicle on the basis ofalready known rewarming effects of the HC dosing system. The rewarmingeffects may be determined on the basis of predicted energy storage inthe HC dosing system.

The feed device of the method may comprise a feed device adapted tosupplying fuel to an injection system of an engine. This makes itpossible for an existing feed device of the vehicle to be utilised for anew purpose. Alternatively, a separate feed device may be employed.

The method may comprise the step of powering said dosing unit by meansof a compressed air source.

The method may comprise the step of cooling said fuel dosing unit bymeans of fuel after cessation of an exhaust flow.

The method is easy to implement in existing motor vehicles. Softwarepertaining to an HC dosing system for exhaust cleaning according to theinvention may be installed in a control unit of the vehicle during themanufacture of the vehicle. A purchaser of the vehicle may thus have thepossibility of selecting the function of the method as an option.Alternatively, software which comprises programme code for applying theinnovative method pertaining to an HC dosing system for exhaust cleaningmay be installed in a control unit of the vehicle on the occasion ofupgrading at a service station, in which case the software may be loadedinto a memory in the control unit. Implementing the innovative method istherefore cost-effective, particularly since the vehicle need not beprovided with any further components or subsystems. Relevant hardware iscurrently already provided in the vehicle. The invention thereforerepresents a cost-effective solution to the problems indicated above.

Software comprising programme code for the cooling a fuel dosing unit bymeans of fuel supplied to the dosing unit, and for intermittentlyrunning a feed device for said fuel at reduced power compared withordinary operation, according to an aspect of the invention, is easy toupdate or replace. Various parts of the software comprising programmecode for applying the innovative method may also be replacedindependently of one another. This modular configuration is advantageousfrom a maintenance perspective.

An aspect of the invention proposes an HC dosing system for exhaustcleaning which comprises a coolable dosing unit for fuel and a feeddevice to supply said fuel, comprising means for cooling a fuel dosingunit by means of fuel intended to be supplied to it, and means forintermittently, in mutually successive periods of running at certainoperating powers and of zero operating power, running said feed deviceto supply said coolant fuel at reduced power compared with ordinaryoperation.

The feed device may be adapted to being run at reduced power comparedwith ordinary operation.

The feed device may adapted to being run intermittently with apredetermined interval configuration.

Said predetermined interval configuration may entail catering forrewarming effects of said dosing unit.

The feed device may be adapted to being activated on the basis of ameasured temperature of at least one portion of said HC dosing system.

The feed device may be adapted to effecting, during operation, coolingof said dosing unit to a temperature which is below a predeterminedlimit value.

The feed device of the method may comprise a feed device adapted tosupplying fuel to an injection system of an engine. This makes itpossible for an existing feed device of the vehicle to be utilised for anew purpose. Alternatively, a separate feed device may be used.

The HC dosing system may comprise compressed air means adapted topowering said dosing unit.

The HC dosing system may comprise means for cooling said fuel dosingunit by means of fuel after cessation of an exhaust flow.

Said HC dosing system may comprise a DPF system.

The above objects are also achieved with a motor vehicle which comprisesan HC dosing system. The vehicle may be a truck, bus or passenger car.

An aspect of the invention proposes any suitable platform whichcomprises an HC dosing system, e.g. a watercraft. The watercraft may beof any kind, e.g. a motorboat, a steamer, a ferry or a ship.

An aspect of the invention proposes a computer programme for cooling adosing unit pertaining to HC dosing systems for exhaust cleaning whichcomprise the dosing unit for fuel and a feed device to supply said fuelfor cooling, which programme contains programme code for causing anelectronic control unit or another computer connected to the electroniccontrol unit to perform steps according to any of claims 1-9.

An aspect of the invention proposes a computer programme for cooling adosing unit pertaining to HC dosing systems for exhaust cleaning whichcomprise the dosing unit for fuel and a feed device to supply said fuelfor cooling, which programme contains programme code stored on acomputer-readable medium for causing an electronic control unit oranother computer connected to the electronic control unit to performsteps according to any of claims 1-9.

An aspect of the invention proposes a computer programme productcontaining a programme code stored on a computer-readable medium forperforming method steps according to any of claims 1-9 when saidprogramme is run on an electronic control unit or another computerconnected to the electronic control unit.

Further objects, advantages and novel features of the present inventionwill become apparent to one skilled in the art from the followingdetails, and also by putting the invention into practice. Whereas theinvention is described below, it should be noted that it is notrestricted to the specific details described. Specialists having accessto the teachings herein will recognise further applications,modifications and incorporations within other fields, which are withinthe scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

For fuller understanding of the present invention and further objectsand advantages of it, the detailed description set out below should beread together with the accompanying drawings, in which the samereference notations denote similar items in the various diagrams, and inwhich:

FIG. 1 illustrates schematically a vehicle according to an embodiment ofthe invention;

FIG. 2 illustrates schematically a subsystem for the vehicle depicted inFIG. 1, according to an embodiment of the invention;

FIG. 3 a is a schematic diagram of operating power of a feed device as afunction of time, according to an embodiment of the invention;

FIG. 3 b is a schematic diagram of operating power of a feed device as afunction of time, according to an embodiment of the invention;

FIG. 4 a is a schematic flowchart of a method according to an embodimentof the invention;

FIG. 4 b is a more detailed schematic flowchart of a method according toan embodiment of the invention; and

FIG. 5 illustrates schematically a computer according to an embodimentof the invention.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a side view of a vehicle 100. The exemplified vehicle 100comprises a tractor unit 110 with an engine 150 and a trailer 112. Thevehicle may be a heavy vehicle, e.g. a truck or a bus. The vehicle mayalternatively be a passenger car.

It should be noted that the invention is applicable to any suitable HCdosing system and is therefore not restricted to DPF systems of motorvehicles. The innovative method and the innovative HC dosing systemaccording to an aspect of the invention are well suited to otherplatforms which have an HC dosing system than motor vehicles, e.g.watercraft. The watercraft may be of any kind, e.g. motorboats,steamers, ferries or ships.

The innovative method and the innovative HC dosing system according toan aspect of the invention are also well suited to for example, systemswhich comprise industrial engines and/or engine-powered industrialrobots.

The innovative method and the innovative HC dosing system according toan aspect of the invention are also well suited to various kinds ofpower plants, e.g. an electric power plant comprising a dieselgenerator.

The innovative method and the innovative HC dosing system are wellsuited to any engine system which comprises an engine and an HC dosingsystem, e.g. on a locomotive or some other platform.

The innovative method and the innovative HC dosing system are wellsuited to any system which comprises a particle generator (e.g. acombustion engine) and an HC dosing system.

The innovative method and the innovative HC dosing system are wellsuited to any system which comprises any kind of system which generatesexhaust gases with particles and a filter which stores particles, whichparticles are burnt during regeneration of said filter, particularlyduring active regeneration of said filter.

The term “link” refers herein to a communication link which may be aphysical connection such as an opto-electronic communication line, or anon-physical connection such as a wireless connection, e.g. a radio linkor microwave link.

The term “line” refers herein to a passage for holding and conveying afluid, e.g. a fuel in liquid form. The line may be a pipe of anysuitable size. The line may be made of any suitable material, e.g.plastic, rubber or metal.

The term “fuel” refers herein to an agent used for active regenerationof a particle filter of an HC dosing system. Said fuel according to aversion is diesel fuel. Other kinds of hydrocarbon-based fuels may ofcourse be used. Diesel fuel is herein cited as an example of a fuel, butone skilled in the art will appreciate that the innovative method andthe innovative HC device are feasible for other types of fuels, e.g.synthetic fuels, subject to necessary adaptations, e.g. adaptations toadequate carbonisation temperatures for fuels adopted, in controlalgorithms for executing software code in accordance with the innovativemethod.

Although the term “HC dosing system” is used herein to denote a particlefilter system, the invention is not restricted to use of a dieselparticle filter. On the contrary, other types of particle filter may beused according to the invention. One skilled in the art will appreciatewhich kind of fuel is most suitable for regenerating the particle filteradopted.

FIG. 2 depicts a subsystem 299 of the vehicle 100. The subsystem 299 issituated in the tractor unit 110. The subsystem 299 may form part of anHC dosing system. The subsystem 299 consists according to this exampleof a container 205 adapted to containing a fuel. The container 205 isadapted to containing a suitable amount of fuel and to beingreplenishable as necessary. The container may accommodate, for example,200 or 1500 litres of fuel.

A first line 271 is adapted to leading the fuel to a pump 230 from thecontainer 205. The pump 230 may be any suitable pump. The pump 230 maybe a diaphragm pump provided with at least one filter. The pump 230 isadapted to being driven by an electric motor. The pump 230 is adapted todrawing the fuel from the container 205 via the first line 271 andsupplying it via a second line 272 to a dosing unit 250. The dosing unit250 comprises an electrically controlled dosing valve by means of whicha flow of fuel added to the exhaust system can be controlled. The pump230 is adapted to pressurising the fuel in the second line 272. Thedosing unit 250 is provided with a throttle unit against which saidpressure of the fuel is built up in the subsystem 299.

The dosing unit 250 is adapted to supplying said fuel to an exhaustsystem (not depicted) of the vehicle 100. More specifically, the dosingunit 250 is adapted to supplying a suitable amount of fuel in acontrolled way to an exhaust system of the vehicle 100. According tothis version, a particle filter (not depicted), e.g. a DPF, is situateddownstream of a location in the exhaust system where supply of fuel iseffected. The amount of fuel supplied in the exhaust system is intendedto be used in a conventional way in the HC dosing system for activeregeneration of the particle filter.

The dosing unit 250 is situated adjacent to, for example, an exhaustpipe which is adapted to leading exhaust gases from the combustionengine 150 of the vehicle 100 to said particle filter. The dosing unit250 is situated in thermal contact with the exhaust system of thevehicle 100. This means that thermal energy stored in, for example, anexhaust pipe, silencer, particle filter and SCR catalyst can thus be ledto the dosing unit 250.

The dosing unit 250 is provided with an electronic control card which isadapted to handling communication with the control unit 200. The dosingunit 250 comprises also plastic and/or rubber components which mightmelt or be otherwise adversely affected as a result of too hightemperatures.

The dosing unit 250 is sensitive to temperatures above a certain value,e.g. 120 degrees Celsius. As for example the exhaust pipe, the silencerand the particle filter of the vehicle 100 exceed this temperaturevalue, there is risk that the dosing unit 250 might become overheatedduring or after operation of the vehicle if not provided with cooling.

A third line 273 runs between the dosing unit 250 and the container 205.The third line 273 is adapted to leading back to the container 205 acertain amount of the fuel fed to the dosing valve 250. Thisconfiguration achieves with advantage cooling of the dosing unit 250.The dosing unit 250 is thus cooled by a flow of the fuel when it ispumped through the dosing unit 250 from the pump 230 to the container205.

The first control unit 200 is arranged for communication with atemperature sensor 220 via a link 293. The temperature sensor 220 isadapted to detecting a prevailing temperature of the fuel where thesensor is fitted. According to this version, the temperature sensor 220is situated in the container 205. The temperature sensor 220 is adaptedto continuously sending signals to the first control unit 200 whichcontain information about a prevailing temperature of the fuel.

According to an alternative, the temperature sensor 220 is situatedadjacent to the dosing unit 250 in order to detect a prevailingtemperature there. According to another version, the temperature sensor220 is situated adjacent to the particle filter of the HC dosing systemin order to detect a prevailing temperature there. Any desired number oftemperature sensors may be provided in the subsystem 299 to detect aprevailing temperature adjacent thereto. The temperature sensor/sensors220 is/are adapted to detecting at a suitable location within thesubsystem 299 a prevailing temperature which may serve as a basis forcontrolling operation of the pump 230 in order to cool the dosing unitby means of said flow of fuel.

The first control unit 200 is arranged for communication with the pump230 via a link 292. The first control unit 200 is adapted to controllingoperation of the pump 230 in order for example to regulate the fuelflows within the subsystem 299.

The first control unit 200 is arranged for communication with the dosingunit 250 via a link 291. The first control unit 200 is adapted tocontrolling operation of the dosing unit 250 in order for example toregulate fuel supply to the exhaust system of the vehicle 100. The firstcontrol unit 200 is adapted to controlling operation of the dosing unit250 in order for example to regulate fuel return supply to the container205.

The first control unit 200 is adapted, according to a version, to usingthe signals received which contain a prevailing temperature of the fuelin the region of the temperature sensor 220 and/or a prevailingtemperature of any desired component of the HC dosing system, e.g. thedosing unit, or the subsystem 299 as a basis for controlling the pump230 in accordance with an aspect of the innovative method. Inparticular, the first control unit 200 is adapted, according to aversion, to using the signals received which contain a prevailingtemperature of the fuel in the region of the temperature sensor 220and/or a prevailing temperature of any desired component of the HCdosing system or the subsystem 299 as a basis for controlling operationof the pump 230 intermittently and at reduced power compared withordinary operation, in accordance with an aspect of the innovativemethod.

A second control unit 210 is arranged for communication with the firstcontrol unit 200 via a link 290. The second control unit 210 may bedetachably connected to the first control unit 200. The second controlunit 210 may be a control unit external to the vehicle 100. The secondcontrol unit 210 may be adapted to performing the innovative methodsteps according to the invention. The second control unit 210 may beused to cross-load software to the first control unit 200, particularlysoftware for applying the innovative method. The second control unit 210may alternatively be arranged for communication with the first controlunit 200 via an internal network in the vehicle. The second control unit210 may be adapted to performing substantially similar functions tothose of the first control unit 200, e.g. using the signals receivedwhich contain a prevailing temperature of the fuel in the region of thetemperature sensor 220 and/or a prevailing temperature of any desiredcomponent of the HC dosing system or the subsystem 299 as a basis forcontrolling operation of the pump 230 intermittently and at reducedpower compared with ordinary operation. It should be noted that theinnovative method may be applied by either the first control unit 200 orthe second control 210 or by both the first control unit 200 and thesecond control unit 210.

According to the embodiment schematically illustrated in FIG. 2, thefirst control unit 200 is adapted to controlling operation of the pump230 intermittently and at reduced power compared with ordinary operationin such a way that any amount of electrical energy which may be neededfor cooling the dosing unit 250 to at least one critical temperature asregards safety is smaller than in the state of the art.

According to this version, a compressed air source 260 is provided tosupply compressed air to the dosing unit 250 via a line 261. The dosingunit 250 is adapted to using said compressed air supply to divide morefinely the fuel being dosed. The compressed air may also be used for atleast partly causing the dosing unit to dose said fuel into the exhaustduct. The compressed air may also be used to blow out of, for example,the dosing unit 250 any fuel which may be present therein. This may beeffected during operation of the engine 150 or after the engine 150 hasbeen switched off.

According to a version, the container 205 may be the vehicle's fueltank, in which case portions of the vehicle's existing fuel system areutilised according to the present invention. According to anotherexample, the container may be a separate container, i.e. not the samecontainer as the vehicle's fuel tank.

According to a version, the dosing unit 250 is situated immediatelyadjacent to an exhaust duct of the HC dosing system. According toanother example, the dosing unit 250 is provided with a passive nozzlerunning through said exhaust duct to dose said fuel directly into theexhaust duct.

According to a version, said pump 230 is the same pump as normallygenerates fuel pressure for an injection system of the engine 150.According to another example, said pump 230 is a separate pump, i.e. notthe same pump as normally generates the fuel pressure for the injectionsystem.

According to an example, a precatalyst and/or oxidation catalyst are/isfitted in series with, and upstream of, the particle filter.

FIG. 3 a is a schematic diagram of an operating power P of the feeddevice as a function of time t, according to an embodiment of theinvention.

It illustrates schematically how the feed device 230 may be run on thebasis of a first predetermined interval configuration. According to thefirst interval configuration, the feed device 230 continues, where aneed for cooling of the dosing unit 250 is determined, e.g. aftercessation of the exhaust flow, to be run at an ordinary operating powerP1 until a first time t1. Between the first time t1 and a second timethe operating power P of the feed device 230 is zero (0) and the feeddevice is therefore off or idling. After the second time t2 the feeddevice 230 is run at an ordinary operating power P1 until a third timet3. After the third time t3, the operating power P of the feed device230 is zero (0) and the feed device is therefore off or idling. At afourth time it is found that predetermined criteria are fulfilled andthe feed device therefore continues to be off. At the fourth time t4 itis found that it will not be possible for a prevailing temperature ofthe dosing unit 250 to be increased by rewarming effects to too high atemperature at which there would be risk of its functional degradation.

According to the first predetermined interval configuration, the periodt1-t2 and the period t2-t3 are of substantially equal duration.

It should be noted that various periods for operation and non-operationof the feed device in a predetermined interval configuration may differin length according to a version. It should also be noted that aninterval configuration may also have any suitable number of periods ofoperation and non-operation of the feed device. According to a version,the periods pertaining to operation of the feed device (e.g. the periodt2-t3) are within a range of 30 to 90 seconds. According to a version,the periods relating to operation of the feed device (e.g. the periodt2-t3) are within a range of 1 to 5 minutes. According to a version, theperiods relating to operation of the feed device (e.g. the period t2-t3)are shorter than one (1) minute. According to a version, the periodsrelating to operation of the feed device (e.g. the period t2-t3) arelonger than five (5) minutes.

According to a version, the predetermined interval configuration has alength of the order of 30 minutes. The predetermined intervalconfiguration may be shorter than 30 minutes. The predetermined intervalconfiguration may be longer than 30 minutes.

A version of the invention determines at any desired times in aninterval configuration whether a predetermined criterion is fulfilled,in which case switching off of the feed device 230 may be effected onthat basis. Said predetermined criterion is described in more detailwith reference to FIG. 4 b below.

FIG. 3 b is a schematic diagram of an operating power of the feed deviceas a function of time, according to an embodiment of the invention.

It illustrates schematically how the feed device 230 may be run on thebasis of a second predetermined interval configuration. According to thesecond interval configuration, the feed device 230 continues, where aneed for cooling of the dosing unit 250 is determined, e.g. aftercessation of the exhaust flow, to be run at a reduced operating powerP2, compared with ordinary operation, until a first time t1. Between thefirst time t1 and a second time the operating power P of the feed device230 is zero (0) and the feed device is therefore off or idling. Afterthe second time t2 the feed device 230 is run at operating power P2until a third time t3′. The period t2-t3′ is shorter than the periodt2-t3 described with reference to FIG. 3 a. After the third time t3′,the operating power P of the feed device 230 is zero (0) until a fourthtime t4′ and the feed device is therefore off or idling. The periodt3′-t4′ is shorter than the period t3-t4 described with reference toFIG. 3 a. After the fourth time t4′ the feed device 230 is run atfurther reduced operating power until a fifth time t5. At the fifth timet5 it is determined that predetermined criteria are fulfilled and thefeed device then continues to be off, whereupon the operating powerbecomes zero (0). At the fifth time t5 it is determined that it will notbe possible for a prevailing temperature of the dosing unit 250 to beincreased by rewarming effects to too high a temperature at which therewould be risk of its functional degradation.

FIG. 4 a is a schematic flowchart of a method for cooling a dosing unitpertaining to HC dosing systems for exhaust cleaning which comprise thedosing unit for fuel and a feed device to supply said fuel for cooling,according to an embodiment of the invention. The method comprises afirst step s401. Method step s401 comprises the steps of cooling a fueldosing unit by means of fuel supplied to the dosing unit, and ofintermittently, in mutually successive periods of running at certainoperating powers and of zero operating power, running said fuel feeddevice at reduced power compared with ordinary operation. The methodends after step s401.

FIG. 4 b is a schematic flowchart of a method for cooling a dosing unitpertaining to HC dosing systems for exhaust cleaning which comprise thedosing unit for fuel and a feed device to supply said fuel for cooling,according to an embodiment of the invention.

The method comprises a first step s410. Method step s410 comprises thestep of shutting off an exhaust flow from a combustion engine of thevehicle 100. At this stage, the dosing unit 250 is cooled in an ordinaryway, i.e. at an operating power of the pump 230 which is needed tomaintain the same cooling flow for the dosing unit as during ordinaryoperation. Shutting off the exhaust flow is effected by switching offthe engine of the vehicle 100. It should be noted that the first methodstep s410 is an optional step. The invention is applicable, according toan aspect, to HC dosing systems in which the engine 150 is in operationand therefore provides the HC dosing system with an exhaust flow. Steps410 is followed by a step s420.

Method step s420 comprises the step of evaluating whether there is acontinuing need to cool the dosing unit by means of a flow of the fuelin the HC dosing system. The step of deciding whether there is a need tocontinue said cooling may be based on various parameters. According toan example, deciding whether there is a continuing need for cooling isbased on the signals from the temperature sensor 220 which containinformation about a prevailing temperature of at least one component ofthe HC dosing system or the subsystem 299 of the vehicle 100. If thereis no continuing need for cooling, the method ends. If there is acontinuing need for cooling, a subsequent step s430 is performed.

Method step s430 comprises the step of influencing the operation of thepump 230 in such a way that it is run intermittently. According to aversion, the pump 230 is run intermittently with a predeterminedinterval configuration. According to a version, the pump 230 is runintermittently at an operating power corresponding to ordinaryoperation. According to a version, the pump 230 is run intermittently ata reduced operating power compared with an operating power employed formaintaining a cooling flow of the dosing unit 250 during ordinaryoperation. Step s430 is followed by a step s440.

Method step s440 comprises the step of deciding whether a predeterminedcriterion is fulfilled. The predetermined criterion may be any suitablecriterion. Said criterion may be associated with a predeterminedinterval configuration. Said criterion may be associated with a measuredtemperature of at least one portion of said HC dosing system. Saidcriterion may be associated with rewarming effects of at least oneportion of said HC dosing system. The predetermined criterion may thusbe fulfilled if the operating power of the pump 230 has been controlledin accordance with the predetermined interval configuration, in whichcase it may be assumed that the dosing unit 250 has reached a desiredtemperature at which it needs no further cooling. If a predeterminedtemperature of at least one portion of the HC dosing system has beenreached, after the pump 230 has been run intermittently in a certainway, it may be assumed that the dosing unit 250 has reached a desiredtemperature at which it needs no further cooling. If it is decided atstep s440 that the predetermined criterion is fulfilled, the methodends. If it is decided at step s440 that the predetermined criterion isnot fulfilled, the pump 230 continues to run intermittently, possiblyalso at reduced power compared with ordinary operation, and step s440 isperformed again. The method ends after step s440.

FIG. 5 is a diagram of a version of a device 500. The control units 200and 210 described with reference to FIG. 2 may in a version comprise thedevice 500. The device 500 comprises a non-volatile memory 520, a dataprocessing unit 510 and a read/write memory 550. The non-volatile memory520 has a first memory element 530 in which a computer programme, e.g.an operating system, is stored for controlling the function of thedevice 500. The device 500 further comprises a bus controller, a serialcommunication port, I/O means, an ND converter, a time and date inputand transfer unit, an event counter and an interruption controller (notdepicted). The non-volatile memory 520 has also a second memory element540.

A proposed computer programme P comprises routines for, e.g. aftercessation of exhaust flow, cooling the fuel dosing unit by means of fuelsupplied to it, and for intermittently, in mutually successive periodsof running at certain operating powers and of zero operating power,running a fuel feed device at reduced power compared with ordinaryoperation, according to the innovative method. The programme P may bestored in an executable form or in a compressed form in a memory 560and/or in a read/write memory 550.

Where the data processing unit 510 is described as performing a certainfunction, it means that the data processing unit 510 effects a certainpart of the programme stored in the memory 560, or a certain part of theprogramme stored in the read/write memory 550.

The data processing device 510 can communicate with a data port 599 viaa data bus 515. The non-volatile memory 520 is intended forcommunication with the data processing unit 510 via a data bus 512. Theseparate memory 560 is intended to communicate with the data processingunit 510 via a data bus 511. The read/write memory 550 is adapted tocommunicating with the data processing unit 510 via a data bus 514. Thedata port 599 may for example have the links 290, 291, 292 and 293connected to it (see FIG. 2).

When data are received on the data port 599, they are temporarily storedin the second memory element 540. When input data received have beentemporarily stored, the data processing unit 510 is prepared to effectcode execution as described above. According to a version, signalsreceived on the data port 599 contain information about a prevailingtemperature of at least one portion of the HC dosing system. The signalsreceived on the data port 599 may be used by the device 500 to run thepump 230 intermittently according to an aspect of the invention. Thesignals received on the data port 599 may used by the device 500 to runthe pump 230 intermittently with a predetermined interval configuration,according to an aspect of the invention. The signals received on thedata port 599 may be used by the device 500 to run the pump 230intermittently at reduced operating power compared with ordinaryoperation and, where applicable, with a predetermined intervalconfiguration, according to an aspect of the invention.

Parts of the methods herein described may be effected by the device 500by means of the data processing unit 510 which runs the programme storedin the memory 560 or the read/write memory 550. When the device 500 runsthe programme, methods herein described are executed.

The foregoing description of the preferred embodiments of the presentinvention is provided for illustrative and descriptive purposes. It isnot intended to be exhaustive or to restrict the invention to thevariants described. Many modifications and variants will obviously beapparent to one skilled in the art. The embodiments have been chosen anddescribed in order best to explain the principles of the invention andits practical applications and hence make it possible for specialists tounderstand the invention for various embodiments and with the variousmodifications appropriate to the intended use.

1. A method for cooling a dosing unit pertaining to an HC dosing systemfor exhaust cleaning of an engine which generates exhaust when theengine operates, and the engine comprises said dosing unit for fuel anda feed device to supply coolant fuel for cooling; the method comprisingthe steps of: cooling said fuel dosing unit by supplying fuel to saiddosing unit; selectively running said feed device at a first operatingpower or at a zero operating power, which comprises intermittentlyrunning said feed device, in mutually successive respective periods ofzero operating power and then running at certain operating powers,comprising running said fuel feed device at a reduced power comparedwith ordinary operation of said feed device.
 2. A method according toclaim 1, wherein said feed device is configured and operable to runintermittently with a predetermined interval configuration.
 3. A methodaccording to claim 2, wherein said predetermined interval configurationof said feed device entails catering for rewarming effects of saiddosing unit.
 4. A method according to claim 1, further comprisingmeasuring a temperature of at least one portion of said HC dosing systemand operating said feed device based on the measured temperature.
 5. Amethod according to claim 1, further comprising operating said feeddevice for cooling said dosing unit to a temperature below apredetermined limit value.
 6. A method according to claim 1, whereinsaid fuel is diesel fuel or another hydrocarbon-based fuel.
 7. A methodaccording to claim 1, wherein said feed device is configured andoperable to supply fuel to an injection system of an engine, or is aseparate feed device.
 8. A method according to claim 1, furthercomprising powering said dosing unit with a compressed air source.
 9. Amethod according to claim 1, further, comprising cooling said fueldosing unit by supplying fuel after cessation of an exhaust flow fromthe engine.
 10. An HC dosing system for exhaust cleaning of a an enginewhich generates an exhaust flow when the engine operates, and the dosingsystem comprises a coolable dosing unit for fuel and a feed device tosupply said fuel; said dosing system comprising: a device for coolingsaid fuel dosing unit by supplying fuel to said dosing unit; and acontrol device for intermittently running said feed device, in mutuallysuccessive respective periods, of zero operating power and then runningat certain operating powers comprising running said feed device tosupply said coolant fuel at reduced power as compared with supply ofcoolant fuel at ordinary operation of said feed device.
 11. An HC dosingsystem according to claim 10, in which said feed device is configuredand operable to being run intermittently with a predetermined intervalconfiguration for powered operation and zero power operation.
 12. An HCdosing system according to claim 11, wherein said predetermined intervalconfiguration for said feed device entails catering for rewarmingeffects of said dosing unit.
 13. An HC dosing system according to claim10, further comprising a temperature measurement device located andconfigured for measuring temperature of at least one portion of said HCdosing system, and said feed device is configured for operation of saidfeed device based on the measured temperature.
 14. An HC dosing systemaccording to claim 10, wherein said feed device is configured forcooling said dosing unit to a temperature which is below a predeterminedlimit value during its operation.
 15. An HC dosing system according toclaim 10, wherein said fuel is diesel fuel or another hydrocarbon-basedfuel.
 16. An HC dosing system according to claim 10, wherein said engineincludes an injection system for fuel, and said feed device suppliesfuel to said injection system of an engine or said feed device is aseparate feed device.
 17. An HC dosing system according to claim 10,further comprising compressed air supply to power said dosing unit. 18.An HC dosing system according to claim 10, comprising: a further coolingdevice configured for cooling said fuel dosing unit by feeding fuelafter cessation of an exhaust flow.
 19. An HC dosing system according toclaim 10, which system comprises a DPF system.
 20. A motor vehiclecomprising an HC dosing system according to claim
 10. 21. A motorvehicle according to claim 20, comprising a truck, bus or passenger car.22. A computer programme product pertaining to an HC dosing system forexhaust cleaning of an engine which generates exhaust when operating,wherein said dosing system comprises a dosing unit for fuel and a feeddevice for the fuel, and wherein said programme product comprisesnon-transitory programme code with non-transitory program instructionsfor causing a computer system to perform steps according to claim 1 onan electronic control unit or causing another computer connected to theelectronic control unit to perform such steps when instructions in saidcode are run on said computer system.
 23. A computer programme productaccording to claim 22, wherein the product contains a programme codestored on a non-transitory computer-readable medium which can be read bysaid computer system for performing method steps when said computerprogramme is run on an electronic control unit or another computerconnected to said electronic control unit.